Lens Chip Q

[Tristin]

I am looking at possibly purchasing a 200mm f/4 Ai-s that is chipped, but apparently the chip came from a 300mm f/4.  Aside from the focal length reporting incorrectly, the seller says it works perfectly fine.  Would this effect anything I am unaware of?  Bjorn mentioned that chipping lenses can improve metering, does that involve the reported focal length?  Thanks in advance.

[Øivind Tøien]

Sounds like it uses a standard Nikon contact block. It would be very easy to replace the chip itself with a custom chip from Bjørn to get correct EXIF and correct exit pupil data (that will potentially improve exposure).

[Bjørn Rørslett]

Please help us by showing a picture of the rear end of the lens. This is to show the contact block arrangement.

As Øivind already noted, given that a standard Nikon block is used it'll be easy to replace the present CPU with a new one specifying the true lens parameters.

[Tristin]

So the incorrect focal length won't effect exposure until I am able to get it corrected?

[Bjørn Rørslett]

Ouch. The chipping operator must be a true amateur ... You need to clean up any remaining burrs or grades from those screw holes. Otherwise they can damage the lens mount over time.

Otherwise, yes incorrect focal length basically influences little on the actual exposure unless you opt for P or S modes. But as the chip actually might be from the "wrong" lens, chances are high the exit pupil data is off and *that* will make metering less precise.

[Tristin]

Much appreciation for the information,  I will get a non-chipped copy.  I have been using non-chipped Ai-s for years so I will be just fine for now.